The present invention relates to the industry of moving, hauling and/or carrying land and the like; and more specifically refers to an equipment called scraper which is used for moving land and similar materials such as mud. More specifically refers to a drag scraper, which is pulled by a tractor. Generally, two methods have been used to solve the problem of land unloading, once it is inside the box of the scraper and must be unload. The first method used is a hinged box, this method basically consists in using the box of the scraper as a container or external box hinged through a couple of bolts and a hydraulic cylinder as an element which rotates the scraper box on its pivots, this allows unloading the land through the mouth of the scraper under the action of gravity.
This method has two variants, one in which that the blade is attached directly to the hinged box of the scraper and therefore travels along therewith during the movement of the scraper (in this case the forces generated during the action of loading the scraper, are transmitted to the bolts on which the scraper box will rotate). Another variant of this method consists in fixing the blade to the outer structure of the scraper, which is the same to which the hinging bolts are fixed (in this solution the blade is firmly attached and can transmit the loading action forces to the entire structure of the machine), in this case the box is fixed and pivoted on a hinge, which is located in the frontal-bottom part of the scraper box, so that only the box floor is “lifted” (tilted) with the rotating movement of the box when unloading the land.
The second method used by the manufacturers of scrapers consists basically of a wall that pushes the material from the rear toward the front of the of the box scraper (ejector). Through the use of one or two hydraulic cylinders this wall is moved to the beginning of the mouth for unloading of the scraper where the material falls the ground under the action of gravity.
Most manufacturers of scrapers currently have chosen to provide the market with scrapers consisting of both methods for unloading the material, mainly due to the best features of one or another according to the type and condition of the ground, in which the scraper will work.
Due to the great variability of soil types and conditions in which the scrapers are used for the agricultural and construction industry, both the pivoting box unloading mechanism as well as the ejector mechanism, face problems with the unloading according to the type and conditions of the soil, making even impossible to use the scraper in some soils with any of these unloading methods, forcing the contractors to have in their inventory both hinged box scrapers and ejector scrapers.
The following known patent documents refer to the technical field of the present invention: U.S. Pat. No. 3,176,863 granted to Kuhl; U.S. Pat. No. 3,533,174 granted to Carston; U.S. Pat. No. 4,366,635 granted to Joyce, Jr; U.S. Pat. No. 4,383,380 granted to Miskin; U.S. Pat. No. 4,388,769 granted to Miskin; U.S. Pat. No. 4,398,363 granted to Miskin; U.S. Pat. No. 4,553,608 granted to Miskin; U.S. Pat. No. 5,702,227 granted to Berg; U.S. Pat. No. 6,092,316 granted to Brinker; U.S. Pat. No. 6,347,670 granted to Miskin; U.S. Pat. No. 7,707,754 granted to Congdon.
Of these documents, U.S. Pat. Nos. 6,092,316 and 6,347,670 are considered to be the closest prior art. However, these inventions differ from the currently described invention at least for the following reasons. With regards to the lifting mechanism, U.S. Pat. No. 6,092,316 discloses a mechanism of four rear bars resting on the rear wheels, so that when it is actuated, the scraper tilts forward, as shown in FIG. 1 thereof, U.S. Pat. No. 6,347,670 discloses a four rear bars also resting on the rear wheels, so that when it is actuated, the scraper tilts forward, as can be appreciated in FIG. 8. The present application relates to a system that has a frontal parallelogram mechanism and a rear parallelogram mechanism, driven by hydraulic cylinders, which are supported on the front pull and the rear wheels, respectively, allowing the scraper to be raised horizontally so that the cutting blade maintains the same angle throughout the entire travel.
With regards to the ejector, U.S. Pat. No. 6,092,316 is a four-bar mechanism actuated by hydraulic cylinders, which actuates the ejector. The ejector is attached to the structure of the machine by means of links as shown in the FIG. 4. U.S. Pat. No. 6,347,670 fails to describe an ejector. In the present invention, the ejector is contained inside a hinged box, so that when the hinged box is moved to unload the material, the ejector travels with the box. The ejector moves inside the box, actuated by hydraulic cylinders. The ejector is supported by means of wheels and respective rails.
The hinged box in U.S. Pat. No. 6,092,316 is not existent. In U.S. Pat. No. 6,347,670, the box is driven by a tilted cylinder, as shown in the figures, at approximately 45 degrees in a loading position (cylinder fully closed, staying vertically in the unload position (cylinder fully open)). See FIG. 6 of the patent. In the case of the present application, the hinged box rotates together with the ejector since the latter is located inside of the box. The hinged box has its turning point in the hinge that is located in the floor near the cutting blade, and is rotated by two cylinders. One end of the cylinder is attached to the structure of the scraper, while the other end of the cylinder is attached to the top frontal part of the hinged box.
The gate of the patent 316 consists of a link that has a pivot point (58), wherein one end of the cylinder that actuates the link unites at its intermediate approximate distance. The gate is placed is semicircular form at the tip of the link. The other end of the cylinder is attached to the structure of the scraper. When the cylinder is closed, the gate is open and vice versa. In this case, the cylinder is located in the back of the gate. The system of patent 670, is very similar to the above, the difference lies in the fact that the actuating cylinder is located on the frontal part of the gate. The basic difference with both patents lies in that the hinged gate of the present invention comprises three sections that fold down the length of the actuating piston and are hinged.
In the prior art scrapers, the cutting blade is linked to the hinged box and this represents a problem because when the hinged box tilts, it varies the approaching angle modifying thus, the efficiency of the material cut.
When the land is difficult and the scraper gets stuck, something that is quite frequent in this field, the pushing or pulling point on the same varies depending on the position of for example the hinged box, being difficult to be pushed or pulled with for example, another tractor. This represents a further disadvantage in the scrapers of the prior art known until the present invention.